User terminal and radio communication method

ABSTRACT

A terminal is disclosed including a receiver that receives downlink control information that triggers channel state information (CSI) reporting using an uplink shared channel; and a processor that controls the CSI reporting based on a given value and transmission timing of at least one of the uplink shared channel and a delivery acknowledgement signal (HARQ-ACK). In other aspects, a radio communication method for a user terminal is also disclosed.

TECHNICAL FIELD

The present invention relates to a user terminal and a radiocommunication method in next-generation mobile communication systems.

BACKGROUND ART

In the UMTS (Universal Mobile Telecommunications System) network, thespecifications of long-term evolution (LTE) have been drafted for thepurpose of further increasing high speed data rates, providing lowerlatency and so on (see non-patent literature 1). In addition, successorsystems of LTE (referred to as, for example, “LTE-A (LTE-Advanced),”“FRA (Future Radio Access),” “4G,” “5G,” “5G+(plus),” “NR (New RAT (NewRadio Access Technology)),” “LTE Rel. 14,” “LTE Rel. 15 (or laterversions),” and so on) are under study for the purpose of achievingfurther broadbandization and increased speed beyond LTE.

In existing LTE systems (for example, LTE Rel. 13 and earlier versions),downlink (DL) and/or uplink (UL) communication are carried out by using1-ms transmission time intervals (TTIs) (also referred to as “subframes”and so on). This 1-ms TTI is the unit of time it takes to transmit 1channel-encoded data packet, and is the processing unit in, for example,scheduling, link adaptation, retransmission control (HARQ-ACK (HybridAutomatic Repeat reQuest-ACKnowledgment)) and so on. The 1-ms TTIcontains 2 slots.

Also, in existing LTE systems (for example, LTE Rel. 8 to 13), a basestation (eNB (eNode B)) controls the power and scheduling of a userterminal (UE (User Equipment)) based on information reported from theUE. For example, the base station controls the power of the UE based onthe power headroom (also referred to as “PH”) reported from the UE. TheUE includes the PH in a power headroom report (PHR) and transmits this.Also, the base station controls the conditions of scheduling and thelike for the UE based on channel state information (also referred to as“CSI”) reported from the UE. The UE includes CSI in uplink controlinformation (UCI) and transmits this.

CITATION LIST Non-Patent Literature

Non-Patent Literature 1: 3GPP TS36.300 V8.12.0 “Evolved UniversalTerrestrial Radio Access (E-UTRA) and Evolved Universal TerrestrialRadio Access Network (E-UTRAN); Overall Description; Stage 2 (Release8),” April, 2010

SUMMARY OF INVENTION Technical Problem

Envisaging future radio communication systems (for example, LTE Rel. 14or 15, 5G, NR, etc.), research is underway to introduce time units (forexample, TTIs that are shorter than 1-ms TTIs (and that are alsoreferred to as “shortened TTIs,” “short TTIs,” “sTTIs,” “slots,”“minslots” and so forth)) having different time lengths than the 1-mstime units used in existing LTE systems (also referred to as“subframes,” “TTIs,” and so on).

For example, given that time units that are different than existing LTEsystems will be introduced, it is likely that the data scheduling timing(for example, the period from a UL grant to UL data transmission, andthe like) is configured shorter than heretofore. Alternatively, it isalso likely that the timing for transmitting delivery acknowledgmentsignals (also referred to as “HARQ-ACK,” “ACK/NACK,” “A/N,” etc.) inresponse to data, as feedback, will be configured shorter thanheretofore.

Meanwhile, when UE transmits given information (for example, PHR, CSI,etc.), the UE generates and transmits the given information aftertransmission of this given information is commanded (triggered). In thiscase, depending on what processing capabilities (for example, theprocessing time it takes to calculate and/or generate the giveninformation) are required of the UE to generate the given information,the UE may not be able to transmit the given information properly byusing the same mechanism (for example, the timing, etc.) as heretofore.

Unless PHR, CSI and/or others are properly reported from the UE to thebase station, proper UL transmission power control and/or schedulingcontrol are not possible, and a decline in the quality of communicationmight arise as a problem.

The present invention has been made in view of the above, and it istherefore an object of the present invention to provide a user terminaland a radio communication method, whereby the decline in the quality ofcommunication can be prevented even when time units that are shorterthan existing systems are introduced.

Solution to Problem

According to one aspect of the present invention, a user terminal has areceiving section that receives a DL signal and a control section thatcontrols transmission of a UL channel, which is scheduled a first periodafter the DL signal is received, and transmission of given information,and, in this user terminal, based on the first period and a secondperiod, which is needed to generate the given information, at least oneof whether or not to transmit the given information by using the ULchannel, content of the given information to transmit in the UL channel,and the first period is controlled.

Advantageous Effects of Invention

According to the present invention, it is possible to prevent thedecline in the quality of communication time units that are shorter thanexisting systems are introduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram to explain the timing for transmitting PUSCH/PUCCHand reporting of PH;

FIGS. 2A and 2B are diagrams to show examples of scheduling controlbased on the timing for transmitting a UL signal and the processing timefor PHR/CSI;

FIG. 3 is a diagram to show an exemplary schematic structure of a radiocommunication system according to one embodiment of the presentinvention;

FIG. 4 is a diagram to show an exemplary overall structure of a radiobase station according to one embodiment of the present invention:

FIG. 5 is a diagram to show an exemplary functional structure of a radiobase station according to one embodiment of the present invention;

FIG. 6 is a diagram to show an exemplary overall structure of userterminal according to one embodiment of the present invention;

FIG. 7 is a diagram to show an exemplary functional structure of userterminal according to one embodiment of the present invention; and

FIG. 8 is a diagram to show an exemplary hardware structure of a radiobase station and a user terminal according to one embodiment of thepresent invention.

DESCRIPTION OF EMBODIMENTS

Also, given that multiple numerologies and the like are likely to besupported in future radio communication systems, studies are in progressto support time units (also referred to as, for example, “subframes,”“slots,” “minislots,” “subslots,” “transmission time intervals (TTIs),”“radio frames” and so on) that are the same as and/or different fromthose of existing LTE systems (LTE Rel. 13 or earlier versions).

For example, a subframe is a time unit having a given time length (forexample, 1 ms) regardless of which numerology a user terminal uses. Onthe other hand, slots may be defined as units of time that depend onwhat numerology a user terminal uses. For example, if the subcarrierspacing is 15 kHz or 30 kHz, the number of symbols per slot may be 7 or14. Meanwhile, when the subcarrier spacing is 60 kHz or greater, thenumber of symbols per slot may be 14. In addition, a slot may include aplurality of minislots (subslots).

Provided that different time units than existing LTE systems will beintroduced, it may be possible to control the transmission and/orreceipt of signals and/or channels by applying multiple time units tothe steps of data processing such as scheduling (also referred to as“processing types”). As an example, it may be possible to control thesteps of processing by using a first time unit (for example, the slotunit) and a second time unit (for example, the symbol unit or theminislot unit), which is shorter than the first time unit.

When using the first time unit (for example, the slot unit), the timingfor transmitting data and/or HARQ-ACK is controlled in slot units. Forexample, in slot-based scheduling, the UE and/or the base stationcontrol the HARQ-ACK in response to the DL data received in slot #N tobe transmitted as feedback in slot #N+K1. In this case, it is likelythat all UEs support K1≥1. Note that the configuration may be employedhere in which some UEs support K1=0.

For example, in slot-based scheduling, the UE and/or the base stationcontrol the HARQ-ACK in response to the DL data received in slot #N tobe transmitted as feedback in slot #N+K2. In this case, it is likelythat all UEs support K1≥2. Note that the configuration may be employedhere in which some UEs support K2=0.

When using a second time unit (for example, the symbol unit), it isnecessary to take into account the processing time by the UE in symbolunits, not in slot units. For example, the timing for transmittingdelivery acknowledgment signals (HARQ-ACK, A/N, etc.) in response to DLdata as feedback and the timing for scheduling UL data in response to ULgrants is controlled in units of symbols. In this case, the processingLime for generating UL data and/or HARQ-ACK in the UE needs to becontrolled in symbol units (N1 and N2), instead of slot units (K).

Here, N1 refers to the number of symbols that the UE has to process,after DL data (PDSCH) is received in the UE, by the earliest time theA/N transmission in response to the PDSCH can be started. N2 refers tothe number of symbols that the UE has to process, after downlink controlinformation to carry a UL transmission command (UL grant) is received,by the earliest time the UL data (PUSCH) transmission scheduled by theUL grant can be started. Note that N1 may be considered the number ofsymbols required in the A/N transmission process, and N2 may beconsidered the number of symbols required in the UL data transmissionprocess.

A configuration may be employed here in which N1 and/or N2 (hereafteralso referred to as “N1/N2”) do not contain other time information suchas timing advance (TA). Alternatively, a configuration may be employedhere in which some time information (for example, UL/DL switching timein the UE) is included in N1/N2.

Furthermore, N1/N2 may be values that are configured in advance, or maybe reported from the UE, as its capability information, to the basestation. When N1/N2 are configured in advance, N1/N2 may be reported tothe UE, in advance, by using higher layer signaling and/or the like, orN1/N2 may be defined in the specification on a fixed basis.

Now, in existing LTE, UE transmits a PHR, which contains PH informationper serving cell, to an eNB, as feedback. This PHR is transmitted viaMAC signaling, by using the PUSCH. To be more specific, a PHR isconstituted by PHR MAC CEs (Control Elements) contained in MAC PDU(Protocol Data Unit). The eNB can control UE's uplink transmissionpower, dynamically, based on PHRs. Note that the PH information may bethe value of PH, or may be an index that is associated with the value(or the level) of PH.

A PHR includes, for example, a PH, which is information to represent thedifference between the total transmission power of the user terminal andthe maximum allowable transmission power, and a PH, which is informationto represent the difference between the transmission power of the userterminal per CC and the maximum allowable transmission power per CC.

Presently, 2 types of PHs (type 1 PH and type 2 PH) are specified. Type1 PH (PH type 1) is the PH based on the power of the PUSCH alone(assuming that only the PUSCH is transmitted). Also, type 2 PH (PH type2) is the PH based on the power of both the PUSCH and the PUCCH(assuming that the PUSCH and the PUCCH are transmitted simultaneously).Existing LTE systems set forth PH type 1 and PH type 2 be calculatedusing a predetermined algorithm.

The eNB may transmit PHR configuration information, which relates to theconditions for transmitting PHRs, to the UE. This information may bereported, for example, via RRC signaling. The UE judges the timing fortransmitting a PHR based on the PHR configuration information reported.That is, a PHR is triggered when the PHR transmission conditions aremet.

Here, for example, 2 timers (a periodic PHR timer and a prohibit PHRtimer) and a path loss change threshold (d1-PathlossChange) can be usedfor the PHR configuration information. For example, when the first timer(prohibit PHR timer) expires and shows that the path loss value on thedownlink has changed from the value upon previous PHR transmission bymore than the path loss change threshold (d1-PathlossChange), a PHR istriggered. Also, when the second timer (periodic PHR timer) expires, aPHR is triggered. Note that the method of triggering a PHR is notlimited to these. For example, triggering of PHRs may be controlled byexplicit and/or implicit reporting.

Furthermore, for CCs where UL transmission takes place, the UE reportsinformation about the PH (real PH) that takes the actual transmissionpower into account, and, for CCs where UL transmission does not takeplace, information about the PH (virtual PH) that does not depend on thePUSCH bandwidth. A PHR to include a real PH may be referred to as a“real PHR,” and a PHR to include a virtual PHR may be referred to as a“virtual PHR.” The eNB can control the power of the UE, by taking intoaccount the uplink transmission power for non-transmitting CCs as wellas transmitting CCs, by receiving information related to real PHRs andvirtual PHRs.

Also, existing LTE systems support aperiodic CSI reporting, in which auser terminal transmits channel state information (CSI) in response to atransmission command from a radio base station. Thistransmission-commanding information (transmission command information,which hereinafter will be referred to as an “A-CSI trigger”) is includedin downlink control information (DCI), which is transmitted in adownlink control channel. DCI to carry an A-CSI trigger may be used forscheduling an uplink shared channel (PUSCH (Physical Uplink SharedCHannel)), and may be also referred to as “DCI format 0 or 4,” an“uplink scheduling grant (hereinafter referred to as an “uplinkgrant”),” and so on.

In aperiodic CSI reporting (A-CSI), a user terminal transmits CSI inresponse to an A-CSI trigger contained in a UL grant, by using the PUSCHspecified by that, UL grant. For example, based on an A-CSI triggercontained in a UL grant, the UE includes CSI in the PUSCH to transmit agiven period later (for example, 4 ms later), and transmits this. CSI tobe transmitted in response to an A-CSI trigger may be referred to as an“aperiodic CSI (A-CSI)” and/or the like. This CSI includes at least oneof a channel quality indicator (CQI), a pre-coding matrix indicator(PMI) and a rank indicator (RI).

In this way, in existing LTE systems, given information such as PHRs andCSI are reported from UE to a base station, so that based on theinformation received, the base station can properly perform at least oneof scheduling, resource allocation and transmission power control.

Meanwhile, as explained earlier, in future radio communication systems,it is anticipated that different time units than existing LTE systemswill be introduced, and, accompanying this, the timing for transmittingdata and/or HARQ-ACK and the like will be configured shorter thanheretofore. Also, in future radio communication systems, it may be alsopossible that the base station will change and control the timing fortransmitting UL data and the timing for transmitting HARQ-ACK, in adynamic manner, in order to configure transmission timings andtransmission periods more flexibly.

For example, FIG. 1 shows a case where UL data (PUSCH) transmission isscheduled in slot #N+4, by downlink control information (DCI) that istransmitted in a given time unit (here, slot #N). Furthermore, FIG. 1shows a case where the A/N (PUCCH) in response to the DL data (PDSCH) ofslot #N+3 is transmitted in slot #N+4. Here, a case is shown in whichPUSCH-PUCCH simultaneous transmission (for example, PCell) takes placein slot #N+4.

When PH is reported in the same manner as in existing systems, UEcalculates (generates) PH type 2, at least with respect to the PCell,and transmits this in slot #N+4.

However, if the base station configures the transmission timing and thetransmission period more flexibly, there is a threat that the UE cannotcalculate PH because there is not enough time for this calculationbefore the slot in which the UE is supposed to report the PH. Forexample, referring to FIG. 1, there is a possibility that PH cannot becalculated by slot #N+4, depending on the UE's capabilities.

Furthermore, studies are in progress to ease the requirement forreporting PH in certain cases. These cases include, for example, thecase where the UE needs to wait for the result of another process (forexample, PDSCH decoding) before configuring the MAC PDU for transmittinga type 2 PHR. In this case, referring to FIG. 1, although the UE needsto calculate a type 2 PH, after having decoded the PDSCH of slot #N+3,the UE may have difficulty calculating and transmitting the PH by slot#N+4, depending on the UE's processing capabilities.

The same is true for channel state information (A-CSI), and, when theperiod from receiving A-CSI-triggering DCI (+PUSCH scheduling) totransmitting a PUSCH is short, the processing time it takes for the UEto generate channel state information cannot be reserved. In this case,it is difficult to include and transmit CSI in the PUSCH.

So, the present inventors have focused on the point that the processingtime it takes for UE to calculate (or generate) given transmittinginformation may vary per UE, and come up with the idea of controllingthe timing for transmitting (for example, scheduling) data, HARQ-ACK,and so on, taking into account the above processing time. Also, thepresent inventors have come up with the idea of controlling whether ornot to transmit given information and/or what content is transmitted,based on the processing time for the given information and the timing(for example, scheduled timing) for transmitting data and/or HARQ-ACK.

Now, embodiments of the present invention will be described below indetail with reference to the accompanying drawings. Note that the radiocommunication methods according to the herein-contained embodiments maybe applied individually or may be applied in combination. Note that, inthe following description, PHRs and CSI will be described as examples ofgiven information reported by UE, the given information that can be usedin the present embodiment is not limited to these, and other signalsand/or channels may be used. Also, in the following description, CSI maybe read as “CSI process.”

First Example

With a first example of the present invention, a case will be describedbelow, in which the timing for transmitting UL data and/or HARQ-ACK andso on are controlled based on information about UE's processingcapabilities for given information. The information about UE'sprocessing capabilities refers to information including informationabout the processing time (for example, the number of symbols and/or theabsolute time (its)) required to calculate (or generate) giveninformation.

A user terminal (UE) transmits information about the processing timerequired for given information to a base station in units smaller thanslots (for example, in symbol units). The processing time for giveninformation may be the time that is required to calculate (or generate)the given information, or may be the time required to transmit the giveninformation. For example, the UE transmits the number of symbols (forexample, N3) to match the PH processing time, to the base station, as UEcapability information. For example, the UE transmits the number ofsymbols (for example, N3) to match the CSI processing time, to the basestation, as UE capability information.

That is, N3 and/or N4 (hereafter, also referred to as “N3/N4”) indicatethe number of OFDM symbols which, when PHR and/or CSI (hereinafter alsoreferred to as “PHR/CSI”) reporting is triggered, the UE needs toprocess after scheduling information is all received, up to the earlieststart position where UL data (PUSCH) transmission can be started.

For information about the processing time required for giveninformation, the UE may report the value of the processing time(absolute time), in addition to the number of symbols to match theprocessing time, to the base station. Also, the UE may transmitinformation about the processing times required for a plurality ofpieces of given information (for example, PHRs and CSIs) together, ormay transmit these separately.

The base station (gNB) controls the transmission timing (for example,scheduling) and/or the UL transmission power based on N3/N4 reportedfrom the UE. For example, the base station controls timing fortransmitting UL data and/or the timing for transmitting HARQ-ACKfeedback based on N3 reported from the UE, and controls the PHRconfiguration and/or the timer for triggering PHRs (also referred to as“PHR configuration information”).

The base station may compare N2, which corresponding to the UEprocessing time from receipt of a UL grant to transmission of thecorresponding UL data, and N3/N4, and control transmission timing(K1/K2) and the like. Now, the method of controlling (or scheduling)transmission timing when N2 is equal to or less than N3/N4 (N2≤N3/N4)will be described below with reference to FIG. 2A. Note that FIG. 2Ashows a case where UL data (PUSCH) is scheduled based on UL grants, anda case where the period (scheduling timing) from receiving a UL grant totransmitting the PUSCH is controlled as K2.

If PUSCH scheduling timing K2 comes later than N2 (case #1 of FIG. 2A),the UE can transmit UL data properly by using the PUSCH.

If PUSCH scheduling timing K2 comes later than N3/N4 (case #2 of FIG.2A), the UE can calculate the PHR/CSI properly, and transmit the PHR/CSIproperly by using the PUSCH. Also, as in case 1 above, the UE cantransmit UL data properly by using the PUSCH.

If PUSCH scheduling timing K2 comes later than N2 and earlier than N3/N4(case #3 of FIG. 2A), the UE can transmit UL data properly by using thePUSCH. Nevertheless, the UE is unable to calculate the PHR/CSI properlybefore transmitting the PUSCH. In this case, the UE does not transmitPHR/CSI that is triggered simultaneously with or after a UL grant, byusing the PUSCH scheduled by that UL grant. Also, a configuration may beemployed here in which the UE does not calculate and/or generate PHR/CSIat all.

If PUSCH scheduling timing K2 comes earlier than N2 (case #4 of FIG.2A), the UE cannot transmit UL data properly by using the PUSCH.Furthermore, the UE is unable to calculate the PHR/CSI properly beforetransmitting the PUSCH.

The base station may control the timing for transmitting UL data and/orthe timing for transmitting HARQ-ACK feedback, per UE, based on N3/N4(+N1/N2) reported from the UE. Furthermore, when at least UL datatransmission from the UE is implemented, the base station may apply thescheduling timing shown in cases 1 to 3. Furthermore, when implementingPHR/CSI reporting, in addition to UL data from the UE, the base stationmay apply the scheduling timing shown in case 2. In this way, bycontrolling the timing of transmission based on UE's processingcapabilities, the UE is able to transmit UL data and PHR/CSI properly.

On the other hand, if N2 is larger than N3/N4 (N2>N3/N4), the basestation may control scheduling, resource allocation, etc. inconsideration of N2 (for example, applying case #2 of FIG. 2B). This isbecause, if UL data is not transmitted properly (as in cases #1, #3 and#4 in FIG. 2B), properly-calculated PHR/CSI cannot be even transmitted.To be more specific, the base station controls the period (K2), in whichthe UE receives a DL signal and performs UL transmission, to come afterN2. In this case, the UE may transmit PHR/CSI triggered at least at orbefore the timing to receive a UL grant, by using the PUSCH that isscheduled by that UL grant.

As described above, by controlling the timing of transmission based onUE's processing capabilities for given information, it is possible totransmit this given information properly. In addition, sufficientprocessing time can be reserved when the UE calculates (or generates)given information, so that the processing load induced by thecalculation and/or the like can be reduced.

Second Example

A second example of the present invention describes the case ofcontrolling whether or not to transmit the given information and/or thecontent of the given information to be transmitted based on UEprocessing capability information for given information and timing fortransmitting UL data and/or HARQ-ACK.

Now that, an example case will be described below, in the followingdescription, in which the timing for transmitting a UL signal (UL dataand/or HARQ-ACK) (K1 and/or K2) is configured to come earlier than agiven value (for example, N3/N4) (for example, case 3 of FIG. 2A). Inaddition, the same is applicable as long as the timing of transmissionis configured without considering UE's processing capabilities for giveninformation.

<Control as to Whether or not to Transmit Given Information>

If a UL signal (for example, PUSCH) is scheduled to be transmittedearlier than a given value, even if PHR/CSI is triggered then, UE cannotreserve time for processing PHR/CSI before transmitting the UL signal.Thus, the UE does not perform UL transmission when the timing forscheduling UL transmission is configured to come earlier than a givenvalue.

For example, at a timing where a UL signal is scheduled, the UE maytransmit only UL data without transmitting PHR/CSI. Alternatively, theUE may not transmit UL data (does not perform UL transmission at all),as well as PHR/CSI. In this case, the UE may not calculate (or generate)PHR/CSI at all. This can reduce the load of transmission processes inthe UE.

When UL data is not transmitted from the UE, or when no triggeredPHR/CSI is contained in a UL signal, the base station may controlretransmission by changing the scheduling timing (for example, byconfiguring the scheduling timing to come later). By this means, uponretransmission, the UE can calculate and transmit PHR/CSI properly.

<Control of Transmission Content of Given Information>

If the timing for scheduling a UL signal is configured to come earlierthan a given value, the UE may change the content of given informationto transmit by using this UL signal and transmit this. That is, the UEselects the content of PHR/CSI based on the scheduling timing. Now, acase will be described below in which the given information is a PHR anda case in which the given information is CSI will be described both.

[PHR]

The UE calculates/generates PH when the timing for scheduling a ULsignal is configured to come earlier than a given value (for example, asin case 3 of FIG. 2A), on the assumption that PUSCH and/or PUCCH are nottransmitted. For example, the UE calculates and transmits a virtual PHtype 1 and/or a virtual PH type 2 on the assumption that no PUSCH and/orPUCCH are transmitted. Note that, to calculate PH, mathematicalequations defined in existing LTE may be used, or newly definedmathematical equations may be used. For example, regardless of how manyPUSCH/PUCCH resources (for example, PRBs) are actually scheduled, a PHRfor when PUSCH and/or PUCCH are transmitted using a given number ofresources, may be calculated/generated.

When multiple CCs are configured (for example, when CA is executed), theUE controls the calculation (or generation) of PHs on a per CC basis.For example, the UE calculates a virtual PH for a CC where the UL signalscheduling timing is configured to come earlier than a given value. Onthe other hand, for a CC where the UL signal scheduling timing isconfigured to come at the same time or later than a given value, the UEmay calculate and transmit real PH type 1 and/or real PH type 2 on theassumption that PUSCH and/or PUCCH are transmitted. By this means, it ispossible to flexibly control the contents of PHRs to transmit per CC, inaccordance with the scheduling timing configured for each CC.

Alternatively, when the timing for scheduling a UL signal is configuredto come earlier than a given value, the UE may calculate one of PH type1 and PH type 2 as a real PH and the other one as a virtual PH. Forexample, the UE may calculate PH type 2 as a real PH and PH type 1 as avirtual PH on the assumption that PUCCH is transmitted and PUSCH is nottransmitted. Accordingly, even when the timing for transmitting anHARQ-ACK in response to a PUSCH scheduled based on a UL grant and thetiming for transmitting an HARQ-ACK in response to a PDSCH scheduledbased on a DL assignment are different, the UE can properly calculate areal PH and a virtual PH according to the respective timings, so thatthe base station can learn the transmission power accurately.

[CSI]

If the timing for scheduling a UL signal is configured to come earlierthan a given value, the UE may include and transmit the latest CSI thathas already been measured, for the CSI measurement signal (or the CSIprocess), in this UL signal. In this case, the base station can controlscheduling, resource allocation and the like based at least on thelatest CSI information held by the UE.

Alternatively, when the timing for scheduling a UL signal is configuredto come earlier than the given value, the UE may include a given value,which is provided in advance, in a UL signal, and transmit this. As forthe given value, information to indicate that CSI (for example, CQI) isout of range (OOR), or a given CSI value that is configured in advancemay be used.

When the base station receives an OOR, the base station can recognizethat the UE could not properly calculate the CSI. By this means, whenthe base station triggers A-CSI again, control such as configuring thescheduling timing later can be implemented. Also, when the base stationreceives a given CSI value, the base station can control the schedulingconditions and the like, based at least on a given CSI value, andrecognize that there is a possibility that the UE has failed tocalculate CSI properly.

When multiple CCs are configured (for example, when CA is executed), theUE controls A-CSI calculation/generation on a per CC basis. For example,in a CC where the timing for scheduling a UL signal is configured tocome earlier than a given value, the UE transmits either the latest CSIheld by the UE, an OOR, or a given CSI value that is configured inadvance. On the other hand, in a CC where the timing for scheduling a ULsignal is configured to come at the same time as or later than a givenvalue, the UE may include and transmit CSI that is calculated based on aCSI trigger, in UL transmission. By this means, it is possible toflexibly control the contents of CSI to transmit per CC, in accordancewith the scheduling timing configured for each CC.

Alternatively, if the timing for scheduling a UL signal is configured tocome earlier than a given value, the UE may be configured so thatwhether or not to transmit CSI and/or the content to transmit aredetermined autonomously on the UE side.

(Radio Communication System)

Now, the structure of a radio communication system according to oneembodiment of the present invention will be described below. In thisradio communication system, communication is performed using one of theradio communication methods according to the herein-containedembodiments of the present invention, or a combination of these.

FIG. 3 is a diagram to show an exemplary schematic structure of a radiocommunication system according to one embodiment of the presentinvention. A radio communication system 1 can adopt carrier aggregation(CA) and/or dual connectivity (DC) to group a plurality of fundamentalfrequency blocks (component carriers) into one, where the LTE systembandwidth (for example, 20 MHz) constitutes 1 unit.

Note that the radio communication system 1 may be referred to as “LTE(Long Term Evolution),” “LTE-A (LTE-Advanced),” “LTE-B (LTE-Beyond),”“SUPER 3G,” “IMT-Advanced,” “4G (4th generation mobile communicationsystem),” “5G (5th generation mobile communication system),” “FRA(Future Radio Access),” “New-RAT (Radio Access Technology)” and so on,or may be seen as a system to implement these.

The radio communication system 1 includes a radio base station 11 thatforms a macro cell C1, and radio base stations 12 (12 a to 12 c) thatare placed within the macro cell C1 and that form small cells C2, whichare narrower than the macro cell C1. Also, user terminals 20 are placedin the macro cell C1 and in each small cell C2. The arrangement andnumber of cells and user terminals 20 are not limited to thoseillustrated in the drawing.

The user terminals 20 can connect with both the radio base station 11and the radio base stations 12. The user terminals 20 may use the macrocell C1 and the small cells C2 at the same time by means of CA or DC.Furthermore, the user terminals 20 may run CA or DC by using a pluralityof cells (CCs) (for example, 5 or fewer CCs or 6 or more CCs).

Between the user terminals 20 and the radio base station 11,communication can be carried out using a carrier of a relatively lowfrequency band (for example, 2 GHz) and a narrow bandwidth (referred toas, for example, an “existing carrier,” a “legacy carrier” and so on).Meanwhile, between the user terminals 20 and the radio base stations 12,a carrier of a relatively high frequency band (for example, 3.5 GHz, 5GHz and so on) and a wide bandwidth may be used, or the same carrier asthat used in the radio base station 11 may be used. Note that thestructure of the frequency band for use in each radio base station is byno means limited to these.

Furthermore, the user terminals 20 can communicate by using timedivision duplexing (TDD) and/or frequency division duplexing (FDD), ineach cell. Furthermore, in each cell (carrier), a single numerology maybe used, or a plurality of different numerologies may be used.

The radio base station 11 and a radio base station 12 (or 2 radio basestations 12) may be connected with each other by cables (for example, byoptical fiber, which is in compliance with the CPRI (Common Public RadioInterface), the X2 interface and so on), or by radio.

The radio base station 11 and the radio base stations 12 are eachconnected with higher station apparatus 30, and are connected with acore network 40 via the higher station apparatus 30. Note that thehigher station apparatus 30 may be, for example, access gatewayapparatus, a radio network controller (RNC), a mobility managemententity (MME) and so on, but is by no means limited to these. Also, eachradio base station 12 may be connected with the higher station apparatus30 via the radio base station 11.

Note that the radio base station 11 is a radio base station having arelatively wide coverage, and may be referred to as a “macro basestation,” a “central node,” an “eNB (eNodeB),” a “transmitting/receivingpoint” and so on. Also, the radio base stations 12 are radio basestations having local coverages, and may be referred to as “small basestations,” “micro base stations,” “pico base stations,” “femto basestations,” “HeNBs (Home eNodeBs),” “RRHs (Remote Radio Heads),”“transmitting/receiving points” and so on. Hereinafter the radio basestations 11 and 12 will be collectively referred to as “radio basestations 10.” unless specified otherwise.

The user terminals 20 are terminals to support various communicationschemes such as LTE, LTE-A and so on, and may be either mobilecommunication terminals (mobile stations) or stationary communicationterminals (fixed stations).

In the radio communication system 1, as radio access schemes, orthogonalfrequency division multiple access (OFDMA) is applied to the downlink,and single-carrier frequency division multiple access (SC-FDMA) and/orOFDMA are applied to the uplink.

OFDMA is a multi-carrier communication scheme to perform communicationby dividing a frequency bandwidth into a plurality of narrow frequencybandwidths (subcarriers) and mapping data to each subcarrier. SC-FDMA isa single-carrier communication scheme to mitigate interference betweenterminals by dividing the system bandwidth into bands formed with one orcontinuous resource blocks per terminal, and allowing a plurality ofterminals to use mutually different bands. Note that the uplink anddownlink radio access schemes are not limited to these combinations, andother radio access schemes may be used as well.

In the radio communication system 1, a downlink shared channel (PDSCH(Physical Downlink Shared CHannel)), which is used by each user terminal20 on a shared basis, a broadcast channel (PBCH (Physical BroadcastCHannel)), downlink L1/L2 control channels and so on are used asdownlink channels. User data, higher layer control information, SIBs(System Information Blocks) and so on are communicated in the PDSCH.Also, the MIB (Master Information Blocks) is communicated in the PBCH.

The downlink L1/L2 control channels include a PDCCH (Physical DownlinkControl CHannel), an EPDCCH (Enhanced Physical Downlink ControlCHannel), a PCFICH (Physical Control Format Indicator CHannel), a PHICH(Physical Hybrid-ARQ Indicator CHannel) and so on. Downlink controlinformation (DCI), which includes PDSCH and/or PUSCH schedulinginformation, is communicated by the PDCCH.

Note that scheduling information may be reported in DCI. For example,DCI to schedule receipt of DL data may be referred to as a “DLassignment,” and DCI to schedule UL data transmission may also bereferred to as a “UL grant.”

The number of OFDM symbols to use for the PDCCH is communicated by thePCFICH. HARQ (Hybrid Automatic Repeat reQuest) delivery acknowledgmentinformation (also referred to as, for example, “retransmission controlinformation,” “HARQ-ACKs,” “ACK/NACKs,” etc.) in response to the PUSCHis transmitted by the PHICH. The EPDCCH isfrequency-division-multiplexed with the PDSCH (downlink shared datachannel) and used to communicate DCI and so on, like the PDCCH.

In the radio communication system 1, an uplink shared channel (PUSCH(Physical Uplink Shared CHannel)), which is used by each user terminal20 on a shared basis, an uplink control channel (PUCCH (Physical UplinkControl CHannel), a random access channel (PRACH (Physical Random AccessCHannel)) and so on are used as uplink channels. User data, higher layercontrol information and so on are communicated by the PUSCH. Also, inthe PUCCH, downlink radio quality information (CQI (Channel QualityIndicator)), delivery acknowledgment information, scheduling requests(SRs) and so on are communicated. By means of the PRACH, random accesspreambles for establishing connections with cells are communicated.

In the radio communication system 1, cell-specific reference signals(CRSs), channel state information reference signals (CSI-RSs),demodulation reference signals (DMRSs), positioning reference signals(PRSs) and so on are communicated as downlink reference signals. Also,in the radio communication system 1, measurement reference signals (SRSs(Sounding Reference Signals)), demodulation reference signals (DMRSs)and so on are communicated as uplink reference signals. Note that theDMRSs may be referred to as “user terminal-specific reference signals(UE-specific reference signals).” Also, the reference signals to becommunicated are by no means limited to these.

(Radio Base Station)

FIG. 4 is a diagram to show an exemplary overall structure of a radiobase station according to one embodiment of the present invention. Aradio base station 10 has a plurality of transmitting/receiving antennas101, amplifying sections 102, transmitting/receiving sections 103, abaseband signal processing section 104, a call processing section 105and a communication path interface 106. Note that one or moretransmitting/receiving antennas 101, amplifying sections 102 andtransmitting/receiving sections 103 may be provided.

User data to be transmitted from the radio base station 10 to a userterminal 20 on the downlink is input from the higher station apparatus30 to the baseband signal processing section 104, via the communicationpath interface 106.

In the baseband signal processing section 104, the user data issubjected to a PDCP (Packet Data Convergence Protocol) layer process,user data division and coupling, RLC (Radio Link Control) layertransmission processes such as RLC retransmission control. MAC (MediumAccess Control) retransmission control (for example, an HARQ (HybridAutomatic Repeat reQuest) transmission process), scheduling, transportformat selection, channel coding, an inverse fast Fourier transform(IFFT) process and a precoding process, and the result is forwarded toeach transmitting/receiving section 103. Furthermore, downlink controlsignals are also subjected to transmission processes such as channelcoding and an inverse fast Fourier transform, and forwarded to eachtransmitting/receiving section 103.

Baseband signals that are pre-coded and output from the baseband signalprocessing section 104 on a per antenna basis are converted into a radiofrequency band in the transmitting/receiving sections 103, and thentransmitted. The radio frequency signals having been subjected tofrequency conversion in the transmitting/receiving sections 103 areamplified in the amplifying sections 102, and transmitted from thetransmitting/receiving antennas 101. The transmitting/receiving sections103 can be constituted by transmitters/receivers, transmitting/receivingcircuits or transmitting/receiving apparatus that can be described basedon general understanding of the technical field to which the presentinvention pertains. Note that a transmitting/receiving section 103 maybe structured as a transmitting/receiving section in one entity, or maybe constituted by a transmitting section and a receiving section.

Meanwhile, as for uplink signals, radio frequency signals that arereceived in the transmitting/receiving antennas 101 are each amplifiedin the amplifying sections 102. The transmitting/receiving sections 103receive the uplink signals amplified in the amplifying sections 102. Thereceived signals are converted into the baseband signal throughfrequency conversion in the transmitting/receiving sections 103 andoutput to the baseband signal processing section 104.

In the baseband signal processing section 104, user data that isincluded in the uplink signals that are input is subjected to a fastFourier transform (FFT) process, an inverse discrete Fourier transform(IDFT) process, error correction decoding, a MAC retransmission controlreceiving process, and RLC layer and PDCP layer receiving processes, andforwarded to the higher station apparatus 30 via the communication pathinterface 106. The call processing section 105 performs call processing(such as setting up and releasing communication channels), manages thestate of the radio base stations 10 and manages the radio resources.

The communication path interface section 106 transmits and receivessignals to and from the higher station apparatus 30 via a predeterminedinterface. Also, the communication path interface 106 may transmit andreceive signals (backhaul signaling) with other radio base stations 10via an inter-base station interface (which is, for example, opticalfiber that is in compliance with the CPRI (Common Public RadioInterface), the X2 interface, etc.).

The transmitting/receiving sections 103 transmit a DL signal (which maybe, for example, downlink control information carrying a UL transmissioncommand (for example, a UL grant) and/or a HARQ-ACK transmissioncommand, downlink data, etc.). The transmitting/receiving sections 103receive given information (for example, PHR, CSI, etc.) by using the ULchannel that is scheduled (or allocated) the first period after the DLsignal is received.

The transmitting/receiving sections 103 may receive information about atleast one of the processing time for HARQ-ACK in response to DL data(PDSCH) (N1), the processing time for UL data (N2), and the processingtime for PH (N3), and the processing time for CSI (N4), as UE capabilityinformation.

FIG. 5 is a diagram to show an exemplary functional structure of a radiobase station according to one embodiment of the present invention. Notethat, although this example primarily shows functional blocks thatpertain to characteristic parts of the present embodiment, the radiobase station 10 has other functional blocks that are necessary for radiocommunication as well.

The baseband signal processing section 104 has a control section(scheduler) 301, a transmission signal generation section 302, a mappingsection 303, a received signal processing section 304 and a measurementsection 305. Note that these configurations have only to be included inthe radio base station 10, and some or all of these configurations maynot be included in the baseband signal processing section 104.

The control section (scheduler) 301 controls the whole of the radio basestation 10. The control section 301 can be constituted by a controller,a control circuit or control apparatus that can be described based ongeneral understanding of the technical field to which the presentinvention pertains.

The control section 301 controls, for example, generation of signals inthe transmission signal generation section 302, allocation of signals inthe mapping section 303, and so on. Furthermore, the control section 301controls signal receiving processes in the received signal processingsection 304, measurements of signals in the measurement section 305, andso on.

The control section 301 controls the scheduling (for example, resourceallocation) of system information, downlink data signals (for example,signals transmitted in the PDSCH) and downlink control signals (forexample, signals transmitted in the PDCCH and/or the EPDCCH, such asdelivery acknowledgment information). Also, the control section 301controls the generation of downlink control signals, downlink datasignals and so on, based on the results of deciding whether or notretransmission control is necessary for uplink data signals, and so on.Also, the control section 301 controls the scheduling of synchronizationsignals (for example, the PSS (Primary Synchronization Signal)/SSS(Secondary Synchronization Signal)), downlink reference signals (forexample, the CRS, the CSI-RS, the DMRS, etc.) and so on.

The control section 301 also controls the scheduling of uplink datasignals (for example, signals transmitted in the PUSCH), uplink controlsignals (for example, signals transmitted in the PUCCH and/or the PUSCH,such as delivery acknowledgment information), random access preambles(for example, signals transmitted in the PRACH), and uplink referencesignals.

The control section 301 controls the timing for transmitting UL dataand/or HARQ-ACK based on information reported from UE (for example,information related to at least one of the processing time for HARQ-ACKin response to DL data (PDSCH) (N1), the processing time for UL data(N2), the processing time for PH (N3) and the processing time for CSI(N4)).

The transmission signal generation section 302 generates downlinksignals (downlink control signals, downlink data signals, downlinkreference signals and so on) based on commands from the control section301, and outputs these signals to the mapping section 303. Thetransmission signal generation section 302 can be constituted by asignal generator, a signal generating circuit or signal generatingapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains.

For example, the transmission signal generation section 302 generates DLassignments, which report downlink data allocation information, and/orUL grants, which report uplink data allocation information, based oncommands from the control section 301. DL assignments and UL grants areboth DCI, in compliance with DCI format. Also, downlink data signals aresubjected to the coding process, the modulation process and otherprocesses based on coding rates, modulation schemes and the like thatare determined based on channel state information (CSI) and the likefrom each user terminal 20.

The mapping section 303 maps the downlink signals generated in thetransmission signal generation section 302 to predetermined radioresources based on commands from the control section 301, and outputsthese to the transmitting/receiving sections 103. The mapping section303 can be constituted by a mapper, a mapping circuit or mappingapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains.

The received signal processing section 304 performs receiving processes(for example, demapping, demodulation, decoding and so on) of receivedsignals that are input from the transmitting/receiving sections 103.Here, the received signals include, for example, uplink signalstransmitted from the user terminal 20 (uplink control signals, uplinkdata signals, uplink reference signals, etc.). For the received signalprocessing section 304, a signal processor, a signal processing circuitor signal processing apparatus that can be described based on generalunderstanding of the technical field to which the present inventionpertains can be used.

The received signal processing section 304 outputs the decodedinformation acquired through the receiving processes, to the controlsection 301. For example, when a PUCCH to contain an HARQ-ACK isreceived, the received signal processing section 304 outputs thisHARQ-ACK to the control section 301. Also, the received signalprocessing section 304 outputs the received signals and/or the signalsafter the receiving processes to the measurement section 305.

The measurement section 305 conducts measurements with respect to thereceived signals. The measurement section 305 can be constituted by ameasurer, a measurement circuit or measurement apparatus that can bedescribed based on general understanding of the technical field to whichthe present invention pertains.

For example, the measurement section 305 may perform RRM (Radio ResourceManagement) measurements, CSI (Channel State Information) measurementsand so on, based on the received signals. The measurement section 305may measure the received power (for example, RSRP (Reference SignalReceived Power)), the received quality (for example, RSRQ (ReferenceSignal Received Quality), SINR (Signal to Interference plus NoiseRatio), etc.), SNR (Signal to Noise Ratio), the signal strength (forexample, RSSI (Received Signal Strength Indicator)), transmission pathinformation (for example, CSI), and so on. The measurement results maybe output to the control section 301.

(User Terminal)

FIG. 6 is a diagram to show an exemplary overall structure of a userterminal according to one embodiment of the present invention. A userterminal 20 has a plurality of transmitting/receiving antennas 201,amplifying sections 202, transmitting/receiving sections 203, a basebandsignal processing section 204 and an application section 205. Note thatone or more transmitting/receiving antennas 201, amplifying sections 202and transmitting/receiving sections 203 may be provided.

Radio frequency signals that are received in the transmitting/receivingantennas 201 are amplified in the amplifying sections 202. Thetransmitting/receiving sections 203 receive the downlink signalsamplified in the amplifying sections 202. The received signals aresubjected to frequency conversion and converted into the baseband signalin the transmitting/receiving sections 203, and output to the basebandsignal processing section 204. A transmitting/receiving section 203 canbe constituted by a transmitters/receiver, a transmitting/receivingcircuit or transmitting/receiving apparatus that can be described basedon general understanding of the technical field to which the presentinvention pertains. Note that a transmitting/receiving section 203 maybe structured as a transmitting/receiving section in one entity, or maybe constituted by a transmitting section and a receiving section.

The baseband signal processing section 204 performs receiving processesfor the baseband signal that is input, including an FFT process, errorcorrection decoding, a retransmission control receiving process and soon. Downlink user data is forwarded to the application section 205. Theapplication section 205 performs processes related to higher layersabove the physical layer and the MAC layer, and so on. In the downlinkdata, the broadcast information can be also forwarded to the applicationsection 205.

Meanwhile, uplink user data is input from the application section 205 tothe baseband signal processing section 204. The baseband signalprocessing section 204 performs a retransmission control transmissionprocess (for example, an HARQ transmission process), channel coding,precoding, a discrete Fourier transform (DFT) process, an IFFT processand so on, and the result is forwarded to the transmitting/receivingsections 203. The baseband signal that is output from the basebandsignal processing section 204 is converted into a radio frequency bandin the transmitting/receiving sections 203. The radio frequency signalsthat are subjected to frequency conversion in the transmitting/receivingsections 203 are amplified in the amplifying sections 202, andtransmitted from the transmitting/receiving antennas 201.

The transmitting/receiving sections 203 receive a DL signal (which maybe, for example, downlink control information carrying a UL transmissioncommand (for example, a UL grant) and/or a HARQ-ACK transmissioncommand, downlink data, etc.). The transmitting/receiving sections 203transmit given information (for example, PHR, CSI, etc.) by using the ULchannel that is scheduled (or allocated) the first period after the DLsignal is received.

The transmitting/receiving sections 203 may transmit information aboutat least one of the processing time for HARQ-ACK in response to DL data(PDSCH) (N1), the processing time for UL data (N2), and the processingtime for PH (N3), and the processing time for CSI (N4), as UE capabilityinformation.

FIG. 7 is a diagram to show an exemplary functional structure of a userterminal according to one embodiment of the present invention. Notethat, although this example primarily shows functional blocks thatpertain to characteristic parts of the present embodiment, the userterminal 20 has other functional blocks that are necessary for radiocommunication as well.

The baseband signal processing section 204 provided in the user terminal20 at least has a control section 401, a transmission signal generationsection 402, a mapping section 403, a received signal processing section404 and a measurement section 405. Note that these configurations haveonly to be included in the user terminal 20, and some or all of theseconfigurations may not be included in the baseband signal processingsection 204.

The control section 401 controls the whole of the user terminal 20. Forthe control section 401, a controller, a control circuit or controlapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains can be used.

The control section 401 controls, for example, generation of signals inthe transmission signal generation section 402, allocation of signals inthe mapping section 403, and so on. Furthermore, the control section 401controls signal receiving processes in the received signal processingsection 404, measurements of signals in the measurement section 405, andso on.

The control section 401 acquires the downlink control signals anddownlink data signals transmitted from the radio base station 10, viathe received signal processing section 404. The control section 401controls the generation of uplink control signals and/or uplink datasignals based on the results of deciding whether or not retransmissioncontrol is necessary for the downlink control signals and/or downlinkdata signals, and so on.

The control section 401 controls transmission of a UL channel that isscheduled a first period after a DL signal is received, and transmissionof given information. For example, the control section 401 controls atleast one of whether or not to transmit given information by using a ULchannel, the content of given information to transmit in the UL channel,and the first period, based on the first period and the second period,which is needed to generate the given information.

Also, when the first period is shorter than a given value (for example,a second period (N3/N4)), the control section 401 exerts control so thatthe given information is not transmitted in the UL channel.Alternatively, when the first period is shorter than a given value andthe given information is a power headroom report, the control section401 may generate a virtual power headroom report on the assumption thatat least no uplink shared channel is transmitted. Alternatively, if thefirst period is shorter than a given value and the given information ischannel state information, the control section 401 may exert control sothat channel state information that has been measured prior to receiptof the DL signal, or a given value, is transmitted.

The transmission signal generation section 402 generates uplink signals(uplink control signals, uplink data signals, uplink reference signals,etc.) based on commands from the control section 401, and outputs thesesignals to the mapping section 403. The transmission signal generationsection 402 can be constituted by a signal generator, a signalgenerating circuit or signal generation apparatus that can be describedbased on general understanding of the technical field to which thepresent invention pertains.

For example, the transmission information generation section 402generates uplink control signals such as delivery acknowledgementinformation, channel state information (CSI) and so on, based oncommands from the control section 401. Also, the transmission signalgeneration section 402 generates uplink data signals based on commandsfrom the control section 401. For example, when a UL grant is includedin a downlink control signal that is reported from the radio basestation 10, the control section 401 commands the transmission signalgeneration section 402 to generate an uplink data signal.

The mapping section 403 maps the uplink signals generated in thetransmission signal generation section 402 to radio resources based oncommands from the control section 401, and output the result to thetransmitting/receiving sections 203. The mapping section 403 can beconstituted by a mapper, a mapping circuit or mapping apparatus that canbe described based on general understanding of the technical field towhich the present invention pertains.

The received signal processing section 404 performs receiving processes(for example, demapping, demodulation, decoding and so on) of receivedsignals that are input from the transmitting/receiving sections 203.Here, the received signals include, for example, downlink signals(downlink control signals, downlink data signals, downlink referencesignals and so on) that are transmitted from the radio base station 10.The received signal processing section 404 can be constituted by asignal processor, a signal processing circuit or signal processingapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains. Also, thereceived signal processing section 404 can constitute the receivingsection according to the present invention.

The received signal processing section 404 outputs the decodedinformation acquired through the receiving processes, to the controlsection 401. The received signal processing section 404 outputs, forexample, broadcast information, system information, RRC signaling, DCIand so on, to the control section 401. Also, the received signalprocessing section 404 outputs the received signals and/or the signalsafter the receiving processes to the measurement section 405.

The measurement section 405 conducts measurements with respect to thereceived signals. The measurement section 405 can be constituted by ameasurer, a measurement circuit or measurement apparatus that can bedescribed based on general understanding of the technical field to whichthe present invention pertains.

For example, the measurement section 405 may perform RRM measurements.CSI measurements, and so on, based on the received signals. Themeasurement section 405 may measure the received power (for example,RSRP), the received quality (for example, RSRQ, SINR, SNR, etc.), thesignal strength (for example, RSSI), transmission path information (forexample, CSI) and so on. The measurement results may be output to thecontrol section 401.

(Hardware Structure)

Note that the block diagrams that have been used to describe the aboveembodiments show blocks in functional units. These functional blocks(components) may be implemented in arbitrary combinations of hardwareand/or software. Also, the method for implementing each functional blockis not particularly limited. That is, each functional block may berealized by 1 piece of apparatus that is physically and/or logicallyaggregated, or may be realized by directly and/or indirectly connectingtwo or more physically and/or logically separate pieces of apparatus(via wire or wireless, for example) and using these multiple pieces ofapparatus.

For example, the radio base station, user terminals and so on accordingto one embodiment of the present invention may function as a computerthat executes the processes of the radio communication method of thepresent invention. FIG. 8 is a diagram to show an example hardwarestructure of a radio base station and a user terminal according to oneembodiment of the present invention. Physically, the above-describedradio base stations 10 and user terminals 20 may be formed as a computerapparatus that includes a processor 1001, a memory 1002, a storage 1003,communication apparatus 1004, input apparatus 1005, output apparatus1006 and a bus 1007.

Note that, in the following description, the word “apparatus” may bereplaced by “circuit,” “device,” “unit” and so on. Note that thehardware structure of a radio base station 10 and a user terminal 20 maybe designed to include one or more of each apparatus shown in thedrawings, or may be designed not to include part of the apparatus.

For example, although only 1 processor 1001 is shown, a plurality ofprocessors may be provided. Furthermore, processes may be implementedwith 1 processor, or processes may be implemented in sequence, or indifferent manners, on one or more processors. Note that the processor1001 may be implemented with one or more chips.

The functions of the radio base station 10 and the user terminal 20 areimplemented by allowing hardware such as the processor 1001 and thememory 1002 to read predetermined software (programs), thereby allowingthe processor 1001 to do calculations, the communication apparatus 1004to communicate, and the memory 1002 and the storage 1003 to read and/orwrite data.

The processor 1001 may control the whole computer by, for example,running an operating system. The processor 1001 may be configured with acentral processing unit (CPU), which includes interfaces with peripheralapparatus, control apparatus, computing apparatus, a register and so on.For example, the above-described baseband signal processing section 104(204), call processing section 105 and so on may be implemented by theprocessor 1001.

Furthermore, the processor 1001 reads programs (program codes), softwaremodules, data and so forth from the storage 1003 and/or thecommunication apparatus 1004, into the memory 1002, and executes variousprocesses according to these. As for the programs, programs to allowcomputers to execute at least part of the operations of theabove-described embodiments may be used. For example, the controlsection 401 of the user terminals 20 may be implemented by controlprograms that are stored in the memory 1002 and that operate on theprocessor 1001, and other functional blocks may be implemented likewise.

The memory 1002 is a computer-readable recording medium, and may beconstituted by, for example, at least one of a ROM (Read Only Memory),an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), aRAM (Random Access Memory) and/or other appropriate storage media. Thememory 1002 may be referred to as a “register.” a “cache,” a “mainmemory” (primary storage apparatus) and so on. The memory 1002 can storeexecutable programs (program codes), software modules and so on forimplementing the radio communication methods according to embodiments ofthe present invention.

The storage 1003 is a computer-readable recording medium, and may beconstituted by, for example, at least one of a flexible disk, a floppy(registered trademark) disk, a magneto-optical disk (for example, acompact disc (CD-ROM (Compact Disc ROM) and so on), a digital versatiledisc, a Blu-ray (registered trademark) disk), a removable disk, a harddisk drive, a smart card, a flash memory device (for example, a card, astick, a key drive, etc.), a magnetic stripe, a database, a server,and/or other appropriate storage media. The storage 1003 may be referredto as “secondary storage apparatus.”

The communication apparatus 1004 is hardware (transmitting/receivingapparatus) for allowing inter-computer communication by using wiredand/or wireless networks, and may be referred to as, for example, a“network device,” a “network controller,” a “network card,” a“communication module” and so on. The communication apparatus 1004 maybe configured to include a high frequency switch, a duplexer, a filter,a frequency synthesizer and so on in order to realize, for example,frequency division duplex (FDD) and/or time division duplex (TDD). Forexample, the above-described transmitting/receiving antennas 101 (201),amplifying sections 102 (202), transmitting/receiving sections 103(203), communication path interface 106 and so on may be implemented bythe communication apparatus 1004.

The input apparatus 1005 is an input device for receiving input from theoutside (for example, a keyboard, a mouse, a microphone, a switch, abutton, a sensor and so on). The output apparatus 1006 is an outputdevice for allowing sending output to the outside (for example, adisplay, a speaker, an LED (Light Emitting Diode) lamp and so on). Notethat the input apparatus 1005 and the output apparatus 1006 may beprovided in an integrated structure (for example, a touch panel).

Furthermore, these pieces of apparatus, including the processor 1001,the memory 1002 and so on are connected by the bus 1007 so as tocommunicate information. The bus 1007 may be formed with a single bus,or may be formed with buses that vary between pieces of apparatus.

Also, the radio base station 10 and the user terminal 20 may bestructured to include hardware such as a microprocessor, a digitalsignal processor (DSP), an ASIC (Application-Specific IntegratedCircuit), a PLD (Programmable Logic Device), an FPGA (Field ProgrammableGate Array) and so on, and part or all of the functional blocks may beimplemented by the hardware. For example, the processor 1001 may beimplemented with at least one of these pieces of hardware.

(Variations)

Note that the terminology used in this specification and the terminologythat is needed to understand this specification may be replaced by otherterms that convey the same or similar meanings. For example, “channels”and/or “symbols” may be replaced by “signals” (or “signaling”). Also,“signals” may be “messages.” A reference signal may be abbreviated as an“RS,” and may be referred to as a “pilot.” a “pilot signal” and so on,depending on which standard applies. Furthermore, a “component carrier(CC)” may be referred to as a “cell,” a “frequency carrier,” a “carrierfrequency” and so on.

Furthermore, a radio frame may be comprised of one or more periods(frames) in the time domain. Each of one or more periods (frames)constituting a radio frame may be referred to as a “subframe.”Furthermore, a subframe may be comprised of one or multiple slots in thetime domain. A subframe may be a fixed time duration (for example, 1 ms)not dependent on the numerology.

Furthermore, a slot may be comprised of one or more symbols in the timedomain (OFDM (Orthogonal Frequency Division Multiplexing) symbols,SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, andso on). Also, a slot may be a time unit based on numerology. Also, aslot may include a plurality of minslots. Each minislot may be comprisedof one or more symbols in the time domain. Also, a minislot may bereferred to as a “subslot.”

A radio frame, a subframe, a slot, a minislot and a symbol all representthe time unit in signal communication. A radio frame, a subframe, aslot, a minislot and a symbol may be each called by other applicablenames. For example, 1 subframe may be referred to as a “transmissiontime interval (TTI),” or a plurality of consecutive subframes may bereferred to as a “TTI,” or 1 slot or minislot may be referred to as a“TTI.” That is, a subframe and/or a TTI may be a subframe (1 ms) inexisting LTE, may be a shorter period than 1 ms (for example, 1 to 13symbols), or may be a longer period of time than 1 ms. Note that theunit to represent the TTI may be referred to as a “slot,” a “minislot”and so on, instead of a “subframe.”

Here, a TTI refers to the minimum time unit of scheduling in radiocommunication, for example. For example, in LTE systems, a radio basestation schedules the radio resources (such as the frequency bandwidthand transmission power that can be used in each user terminal) toallocate to each user terminal in TTI units. Note that the definition ofTTIs is not limited to this.

The TTI may be the transmission time unit of channel-encoded datapackets (transport blocks), code blocks and/or codewords, or may be theunit of processing in scheduling, link adaptation and so on. Note that,when a TTI is given, the period of time (for example, the number ofsymbols) in which transport blocks, code blocks and/or codewords areactually mapped may be shorter than the TTI.

Note that, when 1 slot or 1 minislot is referred to as a “TTI,” one ormore TTIs (that is, one or multiple slots or one or more minslots) maybe the minimum time unit of scheduling. Also, the number of slots (thenumber of minslots) to constitute this minimum time unit of schedulingmay be controlled.

A TTI having a time duration of 1 ms may be referred to as a “normalTTI” (TTI in LTE Rel. 8 to 12), a “long TTI,” a “normal subframe,” a“long subframe.” and so on. A TTI that is shorter than a normal TTI maybe referred to as a “shortened TTI,” a “short TTI,” a “partial TTI” (ora “fractional TTI”), a “shortened subframe,” a “short subframe,” a“minislot,” a “sub-slot” and so on.

Note that a long TTI (for example, a normal TTI, a subframe, etc.) maybe replaced with a TTI having a time duration exceeding 1 ms, and ashort TTI (for example, a shortened TTI) may be replaced with a TTIhaving a TTI length less than the TTI length of a long TTI and not lessthan 1 ms.

A resource block (RB) is the unit of resource allocation in the timedomain and the frequency domain, and may include one or a plurality ofconsecutive subcarriers in the frequency domain. Also, an RB may includeone or more symbols in the time domain, and may be 1 slot, 1 minislot, 1subframe or 1 TTI in length. 1 TTI and 1 subframe each may be comprisedof one or more resource blocks. Note that one or more RBs may bereferred to as a “physical resource block (PRB (Physical RB)).” a“subcarrier group (SCG),” a “resource element group (REG),” a “PRBpair,” an “RB pair” and so on.

Furthermore, a resource block may be comprised of one or more resourceelements (REs). For example, 1 RE may be a radio resource field of 1subcarrier and 1 symbol.

Note that the structures of radio frames, subframes, slots, minslots,symbols and so on described above are merely examples. For example,configurations pertaining to the number of subframes included in a radioframe, the number of slots included per subframe or radio frame, thenumber of minslots included in a slot, the number of symbols and RBsincluded in a slot or a minislot, the number of subcarriers included inan RB, the number of symbols in a TTI, the symbol duration, the lengthof cyclic prefixes (CPs) and so on can be variously changed.

Also, the information and parameters described in this specification maybe represented in absolute values or in relative values with respect togiven values, or may be represented using other applicable information.For example, a radio resource may be specified by a given index.

The names used for parameters and so on in this specification are in norespect limiting. For example, since various channels (PUCCH (PhysicalUplink Control CHannel), PDCCH (Physical Downlink Control CHannel) andso on) and information elements can be identified by any suitable names,the various names assigned to these individual channels and informationelements are in no respect limiting.

The information, signals and/or others described in this specificationmay be represented by using a variety of different technologies. Forexample, data, instructions, commands, information, signals, bits,symbols and chips, all of which may be referenced throughout theherein-contained description, may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orphotons, or any combination of these.

Also, information, signals and so on can be output from higher layers tolower layers and/or from lower layers to higher layers. Information,signals and so on may be input and/or output via a plurality of networknodes.

The information, signals and so on that are input and/or output may bestored in a specific location (for example, in a memory), or may bemanaged in a control table. The information, signals and so on to beinput and/or output can be overwritten, updated or appended. Theinformation, signals and so on that are output may be deleted. Theinformation, signals and so on that are input may be transmitted toother pieces of apparatus.

Reporting of information is by no means limited to theexamples/embodiments described in this specification, and other methodsmay be used as well. For example, reporting of information may beimplemented by using physical layer signaling (for example, downlinkcontrol information (DCI), uplink control information (UCI)), higherlayer signaling (for example, RRC (Radio Resource Control) signaling,broadcast information (the master information block (MIB), systeminformation blocks (SIBs) and so on), MAC (Medium Access Control)signaling and so on), and other signals and/or combinations of these.

Note that physical layer signaling may be referred to as “L1/L2 (Layer1/Layer 2) control information (L1/L2 control signals),” “L1 controlinformation (L1 control signal)” and so on. Also, RRC signaling may bereferred to as “RRC messages,” and can be, for example, an RRCconnection setup message. RRC connection reconfiguration message, and soon. Also, MAC signaling may be reported using, for example, MAC controlelements (MAC CEs (Control Elements)).

Also, reporting of given information (for example, reporting ofinformation to the effect that “X holds”) does not necessarily have tobe sent explicitly, and can be sent in an implicit way (for example, bynot reporting this piece of information, by reporting another piece ofinformation, and so on).

Decisions may be made in values represented by 1 bit (0 or 1), may bemade in Boolean values that represent true or false, or may be made bycomparing numerical values (for example, comparison against a givenvalue).

Software, whether referred to as “software,” “firmware.” “middleware,”“microcode” or “hardware description language.” or called by othernames, should be interpreted broadly, to mean instructions, instructionsets, code, code segments, program codes, programs, subprograms,software modules, applications, software applications, softwarepackages, routines, subroutines, objects, executable files, executionthreads, procedures, functions and so on.

Also, software, commands, information and so on may be transmitted andreceived via communication media. For example, when software istransmitted from a website, a server or other remote sources by usingwired technologies (coaxial cables, optical fiber cables, twisted-paircables, digital subscriber lines (DSL) and so on) and/or wirelesstechnologies (infrared radiation, microwaves and so on), these wiredtechnologies and/or wireless technologies are also included in thedefinition of communication media.

The terms “system” and “network” as used herein are usedinterchangeably.

As used herein, the terms “base station (BS),” “radio base station,”“eNB,” “gNB,” “cell,” “sector,” “cell group,” “carrier,” and “componentcarrier” may be used interchangeably. A base station may be referred toas a “fixed station.” “NodeB,” “eNodeB (eNB),” “access point,”“transmission point,” “receiving point,” “femto cell,” “small cell” andso on.

A base station can accommodate one or more (for example, 3) cells (alsoreferred to as “sectors”). When a base station accommodates a pluralityof cells, the entire coverage area of the base station can bepartitioned into multiple smaller areas, and each smaller area canprovide communication services through base station subsystems (forexample, indoor small base stations (RRHs (Remote Radio Heads))). Theterm “cell” or “sector” refers to part or all of the coverage area of abase station and/or a base station subsystem that provides communicationservices within this coverage.

As used herein, the terms “mobile station (MS)” “user terminal.” “userequipment (UE)” and “terminal” may be used interchangeably. A basestation may be referred to as a “fixed station,” “NodeB,” “eNodeB(eNB),” “access point,” “transmission point.” “receiving point,” “femtocell,” “small cell” and so on.

A mobile station may be referred to, by a person skilled in the art, asa “subscriber station,” “mobile unit,” “subscriber unit,” “wirelessunit,” “remote unit.” “mobile device,” “wireless device.” “wirelesscommunication device.” “remote device,” “mobile subscriber station,”“access terminal,” “mobile terminal,” “wireless terminal,” “remoteterminal,” “handset,” “user agent,” “mobile client,” “client” or someother suitable terms.

Furthermore, the radio base stations in this specification may beinterpreted as user terminals. For example, each aspect/embodiment ofthe present invention may be applied to a configuration in whichcommunication between a radio base station and a user terminal isreplaced with communication among a plurality of user terminals (D2D(Device-to-Device)). In this case, user terminals 20 may have thefunctions of the radio base stations 10 described above. In addition,terms such as “uplink” and “downlink” may be interpreted as “side.” Forexample, an “uplink channel” may be interpreted as a “side channel.”

Likewise, the user terminals in this specification may be interpreted asradio base stations. In this case, the radio base stations 10 may havethe functions of the user terminals 20 described above.

Certain actions which have been described in this specification to beperformed by base stations may, in some cases, be performed by theirupper nodes. In a network comprised of one or more network nodes withbase stations, it is clear that various operations that are performed soas to communicate with terminals can be performed by base stations, oneor more network nodes (for example, MMEs (Mobility Management Entities),S-GWs (Serving-Gateways) and so on may be possible, but these are notlimiting) other than base stations, or combinations of these.

The aspects/embodiments illustrated in this specification may be usedindividually or in combinations, which may be switched depending on themode of implementation. The order of processes, sequences, flowchartsand so on that have been used to describe the aspects/embodiments hereinmay be re-ordered as long as inconsistencies do not arise. For example,although various methods have been illustrated in this specificationwith various components of steps in exemplary orders, the specificorders that are illustrated herein are by no means limiting.

The aspects/embodiments illustrated in this specification may be appliedto LTE (Long Term Evolution), LTE-A (LTE-Advanced), LTE-B (LTE-Beyond),SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system),5G (5th generation mobile communication system), FRA (Future RadioAccess), New-RAT (Radio Access Technology), NR (New Radio), NX (Newradio access), FX (Future generation radio access), GSM (registeredtrademark) (Global System for Mobile communications), CDMA 2000, UMB(Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)),IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB(Ultra-WideBand), Bluetooth (registered trademark), systems that useother adequate radio communication systems and/or next-generationsystems that are enhanced based on these.

The phrase “based on” as used in this specification does not mean “basedonly on,” unless otherwise specified. In other words, the phrase “basedon” means both “based only on” and “based at least on.”

Reference to elements with designations such as “first,” “second” and soon as used herein does not generally limit the number/quantity or orderof these elements. These designations are used herein only forconvenience, as a method for distinguishing between two or moreelements. In this way, reference to the first and second elements doesnot imply that only 2 elements may be employed, or that the firstelement must precede the second element in some way.

The terms “judge” and “determine” as used herein may encompass a widevariety of actions. For example, to “judge” and “determine” as usedherein may be interpreted to mean making judgements and determinationsrelated to calculating, computing, processing, deriving, investigating,looking up (for example, searching a table, a database or some otherdata structure), ascertaining and so on. Furthermore, to “judge” and“determine” as used herein may be interpreted to mean making judgementsand determinations related to receiving (for example, receivinginformation), transmitting (for example, transmitting information),inputting, outputting, accessing (for example, accessing data in amemory) and so on. In addition, to “judge” and “determine” as usedherein may be interpreted to mean making judgements and determinationsrelated to resolving, selecting, choosing, establishing, comparing andso on. In other words, to “judge” and “determine” as used herein may beinterpreted to mean making judgements and determinations related to someaction.

As used herein, the terms “connected” and “coupled,” or any variation ofthese terms, mean all direct or indirect connections or coupling betweentwo or more elements, and may include the presence of one or moreintermediate elements between 2 elements that are “connected” or“coupled” to each other. The coupling or connection between the elementsmay be physical, logical or a combination of these. For example,“connection” may be interpreted as “access.”

As used herein, when 2 elements are connected, these elements may beconsidered “connected” or “coupled” to each other by using one or moreelectrical wires, cables and/or printed electrical connections, and, asa number of non-limiting and non-inclusive examples, by usingelectromagnetic energy, such as electromagnetic energy havingwavelengths in the radio frequency, microwave and optical (both visibleand invisible) regions.

In the present specification, the phrase “A and B are different” maymean “A and B are different from each other.” The terms such as “leave”“coupled” and the like may be interpreted as well.

When terms such as “include,” “comprise” and variations of these areused in this specification or in claims, these terms are intended to beinclusive, in a manner similar to the way the term “provide” is used.Furthermore, the term “or” as used in this specification or in claims isintended to be not an exclusive disjunction.

Now, although the present invention has been described in detail above,it should be obvious to a person skilled in the art that the presentinvention is by no means limited to the embodiments described herein.The present invention can be implemented with various corrections and invarious modifications, without departing from the spirit and scope ofthe present invention defined by the recitations of claims.Consequently, the description herein is provided only for the purpose ofexplaining examples, and should by no means be construed to limit thepresent invention in any way.

The invention claimed is:
 1. A terminal comprising: a receiver thatreceives downlink control information that triggers channel stateinformation (CSI) reporting using an uplink shared channel; and aprocessor that controls the CSI reporting based on: transmission timingof the uplink shared channel, and a timing based on a number of symbolsrequired for calculating the CSI, wherein, when the CSI reporting istriggered, if a start position to transmit the CSI reporting startsearlier than a timing based on the number of symbols required forcalculating the CSI, the processor can control not to transmit theuplink shared channel.
 2. The terminal according to claim 1, whereinwhen the CSI reporting is triggered, if a start position to transmit theCSI reporting starts earlier than the timing based on the number ofsymbols required for calculating the CSI, the processor can control notto perform the CSI reporting.
 3. A radio communication method for aterminate comprising: receiving downlink control information thattriggers channel state information (CSI) reporting using an uplinkshared channel; and controlling the CSI reporting based on: transmissiontiming of the uplink shared channel, and a timing based on a number ofsymbols required for calculating the CSI, wherein, when the CSIreporting is triggered, if a start position to transmit the CSIreporting starts earlier than a timing based on the number of symbolsrequired for calculating the CSI, the terminal can control not totransmit the uplink shared channel.
 4. A system comprising a basestation and a terminal, wherein: the base station comprises: atransmitter that transmits downlink control information that triggerschannel state information (CSI) reporting using an uplink sharedchannel; and the terminal comprises: a receiver that receives thedownlink control information; and a processor that controls the CSIreporting based on: transmission timing of the uplink shared channel,and a timing based on a number of symbols required for calculating theCSI, wherein, when the CSI reporting is triggered, if a start positionto transmit the CSI reporting starts earlier than a timing based on thenumber of symbols required for calculating the CSI, the processor cancontrol not to transmit the uplink shared channel.